Recently, with the improvement of economic conditions, many people have had the ability to travel abroad to see the longed-for landscapes with their own eyes and take pictures of the beauty in sight as a souvenir to remember the scenery by using the smartphones or digital cameras carried with them. However, a series of photos taken of the same site can never compare to a “panoramic photo”, which can record the grandeur of a magnificent view more realistically than separate photos.
As smartphones and digital cameras become more and more affordable, there is almost no tourist without carrying one of them. In addition, since there are lots of image editing software now available in the market, many people have lots of accesses to learn how to combine a series of photos taken of the same site into a panoramic photo through using such software, in order to show the indescribable beauty they witnessed on their journeys. Today, many smartphones and digital cameras also have a “panorama function”, by which to take panoramic photo a user only has to switch the smartphone or digital camera at hand to the “panorama mode” and then to perform a “horizontal scanning” operation, and a panoramic photo will be produced via the image processing software installed in the smartphone or digital camera.
But how to produce such an overwhelming panoramic photo? It must be understood in the first place that a panoramic photo of high image quality is in fact an assembly of a number of photos. More specifically, a plurality of photos of the same scenic spot have to be taken horizontally and consecutively by the smartphone or digital camera and then sequentially stitched together through using a suitable image editing software (e.g., Photoshop) installed in the smartphone or digital camera. Take an ordinary digital single-lens reflex camera as an example. Since the view angle of the lens installed on these ordinary smartphone or digital camera is generally 60 degrees, therefore, at least eight photos must be taken in order to produce a 360-degree panoramic photo of high image quality. Basically, the more photos are stitched together, the better the result. When producing a 360-degree panoramic photo, it is very crucial that each constituent photo has an appropriate portion reserved as an “overlap area”, and the larger the overlap area, the better the stitching result. This is especially true when a lens having a relatively short focal length (e.g., 18 mm, 28 mm, etc.) is used on the smartphone or digital camera because it is difficult to stitch together photos each having a strong sense of perspective, and a more natural stitching result can be obtained in such a difficult situation by taking more photos and making the overlap area as large as possible. To ensure that a 360-degree panoramic photo has high image quality, it is a common practice to take more than ten or even dozens of photos of the same site in a horizontal and consecutive manner, then adjust the brightness and colors of each photo by utilizing suitable image editing software in order to achieve consistency in brightness and hue, then stitch together the overlap areas of each two adjacent photos with the image editing software, and finally trim the sides of the stitched-together photo through the cutting tool provided by the image editing software in order to obtain the desired high-quality 360-degree panoramic photo.
While the foregoing process of taking a series of photos horizontally and successively of the same site and stitching the photos together with image editing software is already a technique frequently used by a few professional photographers to make high-quality 360-degree panoramic photos, however, as an amateur may, even under the guidance of a professional photographer, find it is not only very difficult to determine the number of photos should be taken and the size of the overlap areas should be left on each photo, but also not to mention the complicated editing process that follows, including adjusting the brightness and colors of each photo, stitching the photos together, trimming the composite photo, and so on. It is truly a shame that only few people are capable of using image editing software to combine a series of photos taken horizontally and sequentially of a scenic spot into a 360-degree panoramic photo of high image quality.
Accordingly, the issue to be addressed by the difficulties in determining the number of photos and the size of the overlap areas to be taken is to design a method for producing a panoramic photo by a stitching process, allowing a user to only take two photos and then apply the stitching process to stitch the photos rapidly and precisely together to form a 360-degree panoramic photo of high image quality.
In addition, in recent years, due to the rapid development of electronic technology, the camera features of the smartphones are also becoming very powerful. In order to create differentiations between the smartphones in the markets, the major manufacturers of the smartphones have devoted all their efforts and intelligences in improving the specifications and functions of the cameras on their smartphones, such as enhancing the image pixels, strengthening the selfie function, increasing the aperture, enhancing the optical anti-shake (OIS) function, accelerating the focusing speed and supporting the professional manual mode . . . , etc. Although, the specifications and functions of the cameras on all kinds of smartphones have already be improved a lot than they were used to be several years ago, however, the designs of so-called “dual-lenses” are still being deemed as a mainstream of hardware development needed to be implemented to the cameras of the smartphones by most major manufacturers.
Why do most of the major manufacturers want to develop the “dual-lenses” designs onto the cameras of the smartphones? What would be the features and functions that the “dual-lenses” designs can provide to the smartphones? Please review the situations and needs of the smartphones in current market as follows:
(1) Image capturing limitation of a single-lens: In recent years, the features of pixels, precisions, lens qualities and post-algorithms . . . evolving in the image sensor chips (e.g., CMOS) of the smartphone cameras are increasingly powerful and are gradually reaching to a level threatening the market of professional SLR cameras. However, the slim and light designing trends of the smartphones also cause each of the cameras equipped therewith only capable of utilizing a smaller sized image capturing element (which is an integration of a lens and an image sensor made of wafer) therein due to the size restriction and limited hardware structure of the smartphone. Thus, almost every image capturing element installed in a smartphone adopts a single lens having large aperture and wide angle design, but without having the ability to provide an optical zooming function. In general, the original design function of the camera on the ordinary smartphone is mostly for capturing images of people and near objects under the indoor and low light environments, because the design of large aperture can produce shallow depth of field as well as obtaining better imaging results, but also prone to the problem of insufficient depth of field, in particular, it is easy to cause background or foreground out of a fixedly focused object to be blurred. Therefore, when using the current smartphone camera to capture an image of a magnificent landscape scene, the image being captured will become loose and not sharp enough, and it will also not be easy to capture clear time effect of the image (such as the image of flowing water, car moving track or light graffiti . . . , etc.) and, under sunny and light enough environments, the image being captured is often prone to overexposure problems.
(2) The needs of “dual-lenses” or “multi-lenses”: In recent years, various types of 3D or panoramic films have been broadcasted world-widely in the film market, and are very popular to lots of consumers who are in turn eager to produce 3D or panoramic videos through using their owned smartphones. In response, many of the smartphone manufacturers are dedicating themselves to the research and development relating to the applications of 3D or panoramic cameras, and have launched whole new designed smartphones having the functions of capturing 3D or panoramic videos, such as 360-degree virtual reality (VR) real-time video streaming, the remote end of augmented reality (AR), ultra-high-quality live video broadcast, etc. Since each of the image capturing applications have to be supported by at least two different special lenses, the “dual-lenses” or “multi-lenses” designs are thus becoming to be a requisite accessory on a new generation of smartphones.
(3) Dual-lenses technology unable to achieve a clear and precise optical zooming mechanism: For instance, in 2014, HTC Corporation launched an “One M8” type smartphone having a function of providing the world's first dual depths of field while capturing images, of which the “dual-lenses” technology is built-in with an “Ultra-Pixel with Duo Camera” developed and designed by Altek Corporation, and the “Duo Camera” has a primary lens and a secondary lens installed at the rear surface of the smartphone and capable of working together for capturing images, wherein the primary lens is large than the secondary lens and responsible for capturing the image, and the secondary lens is responsible for recording depth information of the environment, so that a user is able to change the focus position of the image through operating user interface of the smartphone after capturing the image. In November 2015, LG Corporation launched a “V10” type smartphone, which is built-in with an image sensor having 5 million pixels along with a 80-degree normal lens and another image sensor having 5 million pixels along with a 120-degree ultra-wide-angle lens, wherein the dual front lenses design can be chosen to be operated in a standard-angle field of view or a wide-angle field of view at the time of selfie, the 120-degree wide-angle lens can capture the image of the entire background (even the image of a group of people) during selfie, and the 80-degree normal lens can capture the close-up image during selfie. In 2016, LG Corporation released a “G5” type smartphone, of which the dual-lenses design is built-in on the rear surface of the smartphone with an image sensor having 16 million pixels along with a 78-degree normal lens and another image sensor having 8 million pixels along with a 135-degree ultra-wide-angle lens, wherein the 135-degree ultra-wide-angle lens is able to provide a view angle 1.7 times wider (even 15 degrees wider than the view angle of naked eye) than that of the other smartphones in the market, so that a user can use the smartphone to easily capture more image of a scene without having to keep a long distance with the scene. In addition, many science and technology media also predicted that Apple Corporation may release an “iPhone7” in 2016 built-in with dual-lenses design, which may include two image capturing elements having different focal lengths respectively, so as to enable the “iPhone7” to be switched and operated in a standard mode or a remote scene mode for capturing images. However, in view of the above, none of the aforementioned dual-lenses designs is able to achieve clear and precise optical zooming mechanism on behalves of the smartphones.
Why none of the dual-lenses designs implemented in the aforementioned smartphones is able to achieve a clear and precise optical zooming mechanism? The primary reason is that all the aforementioned smartphones are built-in with a standard lens and a wide-angle lens having a large aperture, which will inevitably cause the following problems during the zooming procedure:
(1) Causing image of an object being fixedly focused from a long distance to be blurred: Please refer to FIG. 1, because the standard lens and the wide-angle lens are unable to precisely and fixedly focus on the object 70 (such as the mineral water bottle shown in FIG. 1) from a long distance, so that it will be easy to produce blurred image 71 on the object 70 (such as the blurred text image on the mineral water bottle shown in the right bottom corner of FIG. 1) while the object 70 being zoomed in.
(2) Causing the object 70 within in the images captured in the zooming procedure to abnormally skip between the images: Please refer to FIG. 2, because the corresponding hardware parameters between the standard lens and the wide-angle lens (hereinafter also referring to as an image capturing element) must exist some differences, such as the differences between fields of view (hereinafter referred to as FOV), picture angles . . . and sizes of the corresponding image sensor chips (e.g., CMOS), which inevitably cause the images respectively captured by the standard lens and the wide-angle lens to be different in image ratio, and then cause the corresponding pixels on the images respectively captured by the standard lens and the wide-angle lens to be shifted and have offsets therebetween during the zooming procedure, such as zooming in the object from a zoom ratio of 1.79 (as shown in FIG. 3(A)) to a zoom ratio of 1.80 (as shown in FIG. 3(B)), whereby the object obviously and abnormally skips within the two images (such as causing an obvious and abnormal transition skip from x1 to x2 as shown in FIGS. 3(A) and 3(B), respectively).
In view of the above-mentioned developing evolutions and history of the current dual-lenses smartphones, although the dual-lenses design applications in the current smartphones are quite diverse and differences, such as for enhancing the 3D performance, pulling up the depth of field, tracking face, providing ultra-wide angle, adding pixels, providing multi-apertures . . . and so on, but if the dual-lenses are merely designed to compensate for the lack of a single large aperture wide-angle lens design and do not provide an accurate and clear optical zooming mechanism, it will be very difficult to let the cameras of the smartphones reach to a new level comparable to a professional DSLR camera having the optical zooming function. Accordingly, it is an important issue of the present invention for designing and inventing an image processing equipment or method for enabling an electronic device (such as smartphone or digital camera) having a plurality of image capturing elements installed thereon to promptly perform calibration and verification of intrinsic and extrinsic parameters of the image capturing elements, and to assign the calibrated intrinsic and extrinsic parameters to be the default intrinsic and extrinsic parameters of the image capturing elements, and thereby allowing the electronic device to be able to perform a precise and clear optical zooming mechanism, to perform a precise and clear stitching mechanism for producing a high image quality panoramic image, or to perform a reconstructing mechanism for producing a high quality 3D image through utilizing the images respectively captured by the image capturing elements according to the default intrinsic and extrinsic parameters of the image capturing elements.